The science of Breaking Bad: A No-Rough-Stuff-Type Deal

Breaking Bad : Season 1 : Episode 7: “A No-Rough-Stuff-Type Deal”

Walt and Jesse prepare to make their deal.

After last week’s explosive encounter with Tuco, Walt and Jesse cement their position as Albuquerque’s top suppliers of premium-grade meth. In this post, I’ll be talking about the new cooking process (reductive amination) and producing thermite from an Etch-A-Sketch.

Last episode, Jesse brought Walt’s grand two-pounds-a-week plans crashing down around his ears by pointing out the difficulty of getting pseudoephedrine. If you were to walk into a pharmacy and attempt to buy 400 boxes of decongestant, you would almost certainly find yourself talking to the police very quickly. This is why meth cookers employ small armies of “smurfs” to go out and buy quantities that don’t arouse suspicion, though it does put quite severe limits on the amount of methamphetamine that can be made.

Methylamine.

Faced with this unattractive fact, Walt applies his formidable problem-solving skills and comes up with a different method to make methamphetamine that doesn’t require ephedrine or pseudoephedrine: reductive amination of phenylacetone with methylamine. Jesse greets this plan with the enthusiasm that makes a chemist’s job worthwhile – “Yeah…science!” He might not be so impressed once he find out what these compounds smell like (methylamine in particular gives off a strong fishy odour) – in fact, labs using this method are often busted due to their pervasive stench.

Reductive amination of phenylacetone with methylamine

Compounds that contain nitrogen are often called amines, or given the prefix amino-. Here, we are producing a compound that contains nitrogen (an amine) from one that doesn’t, so the procedure can be classed as an aminiation. We’re removing oxygen from the parent compound, so it can also be classed as a reduction.

Phenylacetone

The government cottoned on to the fact that you can make methamphetamine from phenylacetone quite a long time ago, and made it a controlled substance. Walt clearly knows this, as he doesn’t have Jesse try to buy some but rather opts to make it himself. There are several ways to make phenylacetone, but it sounds like Walt will be reacting phenylacetic acid with acetic acid (the acid that’s in vinegar) as he requires both a tube furnace and a thorium nitrate catalyst (Th(NO3)4); an unusual choice, as it’s radioactive and a manganese-based catalyst should work just as well).

Preparation of phenylacetone from phenylacetic acid and acetic acid

So far, so industrial-scale good. However, our chemists quickly run up against a DEA wall when they find that the anhydrous methylamine they need to do the reductive amination is also a controlled substance. Time to think about producing it from ammonia (NH3) and methanol (CH3OH)? No, it’d make better television to steal it.

Thermite

Just how does one go about recycling an old Etch-A-Sketch? To Jesse, it’s just another piece of junk cluttering up his garage, but to Walt it’s a source of aluminium powder. An Etch-A-Sketch is quite simple in operation – there’s a thin coating of fine aluminium powder sticking to the plastic screen, and the knobs move a stylus that scrapes it off. The lines we see are therefore areas without aluminium powder, which allow us to see through to the dark interior. When the Etch-A-Sketch is shaken, polystyrene beads help to redistribute the powder evenly over the surface of the screen again.

Why is aluminium powder so important? As Walt later explains, he’s making thermite – a mixture of a metal powder and a metal oxide. Such a mixture is not explosive, but will create extremely high temperatures around a small area – it’s often used to weld sections of railway line together in locations inconvenient for conventional welding equipment. The reaction requires some kind of heat source to get started (Walt and Jesse use a gas torch), and then the metal powder is simply oxidised by the oxygen in the metal oxide in a classic redox reaction.

In this episode, Walt is probably using iron(III) oxide due to its easy availability:

Fe2O3 + 2Al → 2Fe + Al2O3 + heat

This reaction would reach around 2500 °C, easily enough to melt through the steel padlock on the storeroom door. Too bad the guys didn’t bring a trolley along.

Walt also makes reference to the Gustav Gun, an enormous railway cannon used by the Wehrmacht against the Soviet Union during World War II. It was destroyed in 1945 to prevent its capture by advancing Allied troops – if a thermite-packing commando had actually disabled it all by himself, someone would have made a film about it by now.

they steal a 55 gallon drum of methylamine. first of all, that would be too heavy for 2 guys. and they carry it instead of roll it?
then it looks like methylamine is a gas above -6 degrees C. so this drum is under pressure? that sounds unlikely.

You can get methylamine in gaseous (or pressurised liquid) form, but it’s usually supplied as a 30 wt% – 40 wt% solution in a solvent like ethanol or methanol. I imagine that this is what our cooks are stealing, though 55 gallons of ethanol would weigh about 165 kg (364 lb) and trying to carry rather than roll it is a guaranteed workplace injury.

Okay, I have a chem question here. How would phenylacetic acid and acetic acid make p2p? I mean, organically speaking, what type of mechanism would it be? A friend and I kept trying to figure this out to no avail and it was driving us crazy. I have only taken a year of o chem, so it may be something I haven’t learned about yet, but we just couldn’t figure out how two carboxylic acids would make a ketone.

There are a few ways to do this reaction, most of the common lab-based ones using organometallic compounds. In Walt’s case, I believe that he’s performing a simple catalytic pyrolysis via a PhC(O)O-Mn-O-Th(O)-OC(O)CH3 intermediate. CO2 and H2O are eliminated and the catalyst is regenerated.